Many types of engines use one or more reciprocating pistons to generate power. For example, an internal combustion engine utilizes combustion of a fuel within combustion chambers to provide motive force to corresponding pistons within the engine. Each piston includes rings that provide a fluid tight seal against a cylinder wall while the piston moves up and down within the cylinder. The fluid tight seal separates the combustion chamber from a crankcase of the engine. Each piston is connected to a connecting rod using a wrist pin. The connecting rods are connected to a crankshaft of the engine. Combustion of the fuel within the combustion chambers creates rapid gas expansion, which moves the pistons linearly within the cylinders. The connecting rods transfer the linear motion of the pistons into rotational crankshaft motion, thus generating power at the crankshaft of the engine.
Several different options are available to retain a wrist pin in its place inside a piston. Clips can be used to clip the wrist pin in place, however, such clips are often difficult to change out quickly and can, in some cases, become dislodged during operation. For engines that are frequently rebuilt, such as racing engines, the wrist pins need to be able to be replaced quickly. For those situations, buttons may be more useful. Buttons slide in and out of corresponding piston bosses easily, so they are easy to change quickly. However, in some racing applications, pistons experience sufficient forces to cause circular buttons to rotate within their corresponding piston bosses. This rotation can impinge on, and perhaps deform, an oil control ring inside an oil control ring groove of the piston, causing engine problems. The engine may then be at a higher risk of failure due to damage to the oil control ring and/or oil control ring groove. As a result, the engine may need to be disassembled more frequently in order repair any damage caused by a damaged or deformed oil control ring and/or oil control ring groove.